The invention relates to a recording/reproduction arrangement for data and command logs in peripheral devices of EDP systems.
Peripheral devices of EDP systems, for example high-performance electrophotographic printers, are connected to the EDP system via an interface module. Data and commands are transmitted from the EDP system, which may be a mainframe (host) for example, to a control device (controller) of the peripheral device. During communications between the mainframe and the control device of the peripheral device, fault and problem messages with respect to the controller, the user of the peripheral device and the software used can occur, which are then displayed, for example, by means of a monitor of the peripheral device. In order for it to be possible for the fault and problem messages (errors) of the high-performance printer to be analyzed by the maintenance department, central service department or the product development department, from time to time it is expedient to record the data and commands transmitted to the control device in the form of a log. Such a recording of data and commands is termed an I/O trace. By comparing the I/O trace with the specification or application, it is then possible to decide whether the present fault message relates to a problem of the peripheral device, a user problem or a software problem. The fault messages to be examined may relate to, for example, an error within the peripheral device (for example a faulty printout in the case of a high-performance electrophotographic printer), an incorrect message from the peripheral device to the EDP system, an error message from the EDP system, or a "system or printer crash". Since the problems described are generally application-specific and occur in the on-line state of the peripheral device, in the interests of economic troubleshooting it must also be possible to reproduce the error in the off-line state of the peripheral device (the off-line state referring to the peripheral device being disconnected from the EDP system as well.
In order to create such an I/O trace for error diagnostics, it is customary for the data and commands to be recorded internally in the system by the EDP system, or--as in the recording/reproduction arrangement for data and command logs in a printing device known from U.S. Pat. No. 4,947,397 by a control program initiated via an operator unit (user interface) of the printing device which controls function procedures in the printing device depending on malfunctions occurring in the control program or the printing device respectively. However, internal system recording is very susceptible to errors and must usually be carried out by the customer. The I/O trace recorded in the on-line state of the peripheral device cannot be used to reproduce the customer situation. In order to be able to reproduce the customer situation, customer data (for example jobs, texts, character sets, overlays, page segments) are stored on tape at the system and are then read out again at a test system (at the central service department for example) for troubleshooting. Since the data storage involves very complex data structures and not all the files necessary for reproducing the customer situation can be readily located, the storage of the data on a tape is very time-consuming and susceptible to errors. It can sometimes take several weeks before the required data is recorded on tape and can be reproduced. However, an error-free reproduction of the error manifestation is not guaranteed even then, since the recorded data and commands are sometimes preprocessed differently in the central service department or in the product development department than in the peripheral device to be serviced.